common-versions.json

This is the template that rush init generates for common-versions.json:

common/config/rush/common-versions.json

/**
 * This configuration file specifies NPM dependency version selections that affect all projects
 * in a Rush repo.  More documentation is available on the Rush website: https://rushjs.io
 */
{
  "$schema": "https://developer.microsoft.com/json-schemas/rush/v5/common-versions.schema.json",

  /**
   * A table that specifies a "preferred version" for a given NPM package.  This feature is typically used
   * to hold back an indirect dependency to a specific older version, or to reduce duplication of indirect dependencies.
   *
   * The "preferredVersions" value can be any SemVer range specifier (e.g. "~1.2.3").  Rush injects these values into
   * the "dependencies" field of the top-level common/temp/package.json, which influences how the package manager
   * will calculate versions.  The specific effect depends on your package manager.  Generally it will have no
   * effect on an incompatible or already constrained SemVer range.  If you are using PNPM, similar effects can be
   * achieved using the pnpmfile.js hook.  See the Rush documentation for more details.
   *
   * After modifying this field, it's recommended to run "rush update --full" so that the package manager
   * will recalculate all version selections.
   */
  "preferredVersions": {
    /**
     * When someone asks for "^1.0.0" make sure they get "1.2.3" when working in this repo,
     * instead of the latest version.
     */
    // "some-library": "1.2.3"
  },

  /**
   * When set to true, for all projects in the repo, all dependencies will be automatically added as preferredVersions,
   * except in cases where different projects specify different version ranges for a given dependency.  For older
   * package managers, this tended to reduce duplication of indirect dependencies.  However, it can sometimes cause
   * trouble for indirect dependencies with incompatible peerDependencies ranges.
   *
   * The default value is true.  If you're encountering installation errors related to peer dependencies,
   * it's recommended to set this to false.
   *
   * After modifying this field, it's recommended to run "rush update --full" so that the package manager
   * will recalculate all version selections.
   */
  // "implicitlyPreferredVersions": false,

  /**
   * If you would like the version specifiers for your dependencies to be consistent, then
   * uncomment this line. This is effectively similar to running "rush check" before any
   * of the following commands:
   *
   *   rush install, rush update, rush link, rush version, rush publish
   *
   * In some cases you may want this turned on, but need to allow certain packages to use a different
   * version. In those cases, you will need to add an entry to the "allowedAlternativeVersions"
   * section of the common-versions.json.
   *
   * In the case that subspaces is enabled, this setting will take effect at a subspace level.
   */
  // "ensureConsistentVersions": true,

  /**
   * The "rush check" command can be used to enforce that every project in the repo must specify
   * the same SemVer range for a given dependency.  However, sometimes exceptions are needed.
   * The allowedAlternativeVersions table allows you to list other SemVer ranges that will be
   * accepted by "rush check" for a given dependency.
   *
   * IMPORTANT: THIS TABLE IS FOR *ADDITIONAL* VERSION RANGES THAT ARE ALTERNATIVES TO THE
   * USUAL VERSION (WHICH IS INFERRED BY LOOKING AT ALL PROJECTS IN THE REPO).
   * This design avoids unnecessary churn in this file.
   */
  "allowedAlternativeVersions": {
    /**
     * For example, allow some projects to use an older TypeScript compiler
     * (in addition to whatever "usual" version is being used by other projects in the repo):
     */
    // "typescript": [
    //   "~2.4.0"
    // ]
  }
}